Effect of food enzymes on utilisation of lupin carbohydrates by broilers

1. The effects of 3 commercial enzyme products on the nutritive value of 2 lupin species were investigated with the emphasis on changes in composition of non-starch polysaccharides (NSPs) along the digestive tract. Enzyme A contained primarily cellulase, beta-glucanase and xylanase activities, enzyme B primarily hemicellulase, pentosanase and xylanase activities, and enzyme C primarily hemicellulase, pectinase and beta-glucanase activities. 2. The enzymes were added to semi-purified diets based on sorghum and casein containing 35% whole seed lupins (Lupinus angustifolius cv Gungurru or Lupinus albus cv Kiev mutant). Control diets contained no lupins. 3. Food conversion ratio (FCR), excreta moisture content and apparent metabolisable energy (AME) were affected by lupin species but not by enzyme supplementation. 4. In diets with L. angustifolius, enzyme C significantly increased digesta viscosity and increased the concentration of soluble NSPs in all sections of the intestine. 5. Digestibility of protein and NSPs in the ileum and microbial fermentation in the ileum and caeca were not affected by adding enzymes to diets containing L. angustifolius. 6. Enzyme addition to diets with L. albus did not affect digesta viscosity nor concentration of soluble NSPs but caused a significantly (P<0.05) reduced concentration of insoluble NSP in the ileum. 7. Enzyme addition to L. albus significantly (P<0.05) increased NSP digestibility in the ileum but had no effects on protein digestibility and fermentation in the ileum and caeca.     

Effects of dietary mineral supplementation on the performance and mineral retentions of broilers at high ambient temperatures

1. The relationship between broiler performance and two dietary mineral balance equations was investigated at a high constant ambient temperature (30°C) using a range of 11 salt supplements given to male broiler chicks from 21 to 42 d of age.

2. No relationship was found between broiler performance and either of the two balance equations.

3. Re‐evaluating these equations using retained, rather than dietary, mineral concentrations did not improve the relationship although changes in mineral retentions associated with the supplements indicated that dietary concentrations were not a good indicator of the impact of the diet on the bird's acid‐base homoeostasis.

4. Evidence was found that metabolisable anions supplemented in association with mineral cations may have a significant effect on broiler performance.     

Free-choice feeding of broilers at high temperatures

Broilers fed complete diets to 21 but not 44 d of age grew faster with a better efficiency of food utilisation than broilers given a free-choice selection of the cereal and protein components. When finisher diets, varying in metabolisable energy (ME) and amino acid:ME ratios, were fed at high ambient temperatures (25 to 35 degrees C) broilers on the free-choice system selected similar amino acid:ME intake ratios, which were lower than the ratios contained in the complete diets. Differences in broiler performance between 22 and 44 d of age reflected variations in ME rather than amino acid intake.     

The effects of food withdrawal and darkening on lipid peroxidation of laying hens in high ambient temperatures

The aim of this study was to investigate the effects of feed withdrawal and darkening on the antioxidative status of laying hens in high ambient temperatures between 30-40 degrees C. We determined vitamins A and E, lipid peroxidation as thiobarbituric-acid reactive substances (TBARS), glutathione peroxidase (GSH-Px) and reduced glutathione (GSH) in the serum, liver and muscle. Sixteen week old hens (Ross Brown) were divided into 3 groups of 30 hens each. The first group was used as a control. Hens in the second (feed withdrawal) group were subjected to feed removal between 14-18 h during the summer. Hens in the third (darkening) group were subjected to darkening of the hens house with black curtains between 14-18 h. At the end of 16 weeks, blood serum, liver and breast muscle samples were taken from all animals and analysed. Vitamins A and E levels in serum and liver were significantly (P < 0.05, P < 0.01) higher in feed withdrawal and darkened groups than in control group whereas the serum levels of the darkening group were highest. GSH-Px activity and GSH level in liver and muscle were also significantly (P < 0.05, P < 0.01) higher in feed withdrawal and the darkening group than in control. However, TBARS levels in liver and muscle were significantly (P < 0.05, P < 0.01) lower in feed withdrawal and darkening groups compared with control group, whereas the level of the darkening group was the lowest. In conclusion, we observed that feed withdrawal and darkening of hens in high temperatures during summertime resulted in an increase of antioxidant enzymes and vitamins levels and in a decrease of lipid peroxidation.     

Inhibition of adrenal steroidogenesis,food restriction and acclimation to high ambient temperatures in chickens

1. White Plymouth Rock chickens placed under 60% food restriction or ad libitum feeding, with or without metyrapone treatment, from either 4 to 6 (early) or 24 to 26 (late) d of age were exposed to high ambient temperatures (35 ± 2°C) from 36 to 43 d of age.

2. Stress attributable to fasting was not manifested through leucocytic alteration when food‐restricted chicks were supplemented with an adrenal blocking chemical, metyrapone.

3. Provision of metyrapone during the fasting period resulted in inferior compensatory growth during refeeding.

4. Exposure to high temperatures from 36 to 43 d of age did not cause an elevation in the heterophihlymphocyte (H/L) ratios of chicks that had eaten metyrapone‐treated food ad libitum during the neonatal stage.

5. During heat exposure, chicks that had been subjected to early 60% restriction with non‐metyrapone‐treated food had lower H/L ratios and improved resistance to marble spleen disease infection.     

Circadian variation in heat production and respiratory quotient in growing broilers maintained at different food intakes and ambient temperatures.

1. Circadian variations in heat production (HP) rate and respiratory quotient (RQ) were measured in growing broilers maintained at 5 ambient temperatures (14 degrees, 17 degrees, 22 degrees, 27 degrees and 32 degrees C) and at 5 rates of feeding [ad libitum intake and 75%, 50%, 25% and 0% (fasting) of ad libitum intake]. 2. In most cases, the HP rate decreased from 10.30 h just after food was given) until 00.30 h (the 1-h dark period), showed an overshoot just after the 1-h dark period and then changed little. 3. Circadian variation in RQ, except in the fasted group, showed a similar pattern, which consisted of increase, decrease and constant phases. 4. Food intake affected the pattern of circadian variation in RQ, although ambient temperature had little effect. Possible effects of food intake on the pattern of circadian variation in HP rate were discussed.     

Relative humidity at moderate ambient temperatures: its effect on male broiler chickens and turkeys

1. The effect of relative humidity (RH, 40% to 75%) at moderate ambient temperatures (Ta, 28 degrees and 30 degrees C) on the performance and thermoregulation of male broiler chickens and turkeys was studied at the age of 4 to 8 weeks. 2. Weight gain and food intake of male broiler chickens were significantly higher at 60% to 65% RH but food conversion efficiency was not affected by RH. In male turkeys, no effect of RH on performance was recorded. 3. Both chickens and turkeys controlled body temperature at normothermic levels during exposure to the experimental environmental conditions. 4. The rate of panting estimated from blood pH and pCO2 was lower in chickens exposed to 28 degrees C than to 30 degrees C. In turkeys, the rate was lower than that recorded in chickens at both Ta(s). 5. Plasma T3 was positively and significantly correlated with food intake. 6. It may be concluded that RH plays a role in the performance of chickens exposed to 30 degrees and 28 degrees C. whereas male turkeys must respond to RH at Ta >30 degrees C.     

Chitin utilisation by broilers and its effect on body composition and blood metabolites

1. Little is known about the ability of farmed poultry to digest chitin and derive nutrients from the ingestion of insects. 2. Commercial chitin derived from crustacean shell waste was found to contain 373 g crude protein, 265 g ash, 23.5 g ether extract, 130 g calcium and 16.4 g phosphorus per kg, on an air-dry basis. 3. It was included in diets at 0, 25, 50 and 75 g chitin per kg and fed to 320 1-d-old broiler males, over a 21-d period. There were no statistically significant treatment effects on weight gain or feed efficiency. Apparent digestibility of chitin protein was 0.48, 0.50 and 0.45, at the 25, 50 and 75 g per kg inclusions, respectively. Mean AME and AMEN values of chitin were determined as 8.97 and 8.86 MJ/kg. 4. In a subsequent study, mean TME and TMEN values of chitin were determined to be 8.23 and 8.21 MJ per kg, respectively. Addition of chitinase to the diet increased TME and TMEN of chitin to 8.81 and 8.79 MJ per kg, respectively (P<0.05). True digestibility of chitin protein was determined to be 0.87. 5. Triglyceride concentrations in liver and breast meat were significantly reduced by chitin inclusion. No significant differences in carcase yield at 21 d of age were found. Serum cholesterol and triglycerol concentrations were reduced significantly by dietary chitin, the lowest levels being observed at the 50 g per kg inclusion level. 6. These findings indicate the ability of modern poultry to digest chitin but suggest that the ingestion of insects is not an important source of nutrients, at least from the exoskeleton.     

Influence of high ambient temperatures on performance of multiparous lactating sows.

Multiparous Large White sows (n = 63) were used to investigate the effects of five ambient temperatures (18, 22, 25, 27, and 29 degrees C) and two dietary protein contents on their lactation performance. At each temperature treatment, ambient temperature was maintained constant over the 21-d lactation period. Dietary protein content was either 14 or 17% with essential amino acids levels calculated not to be limiting. The animals had ad libitum access to feed between the seventh and the 19th day of lactation. Diet composition did not influence lactation performance. Over the 21-d lactation, feed intake decreased from 5.67 to 3.08 kg/d between 18 and 29 degrees C. Between d 7 and 19, the corresponding values were 7.16 and 3.48 kg/d, respectively. This decrease was curvilinear; an equation to predict voluntary feed intake (VFI) from temperature (T, degrees C) and body weight (BW, kg) is proposed: VFI = -49,052 + 1,213 T - 31.5 T2 + 330 BW - .61 BW2 (residual standard deviation: 1,018). Skin temperature increased regularly with increased ambient temperature (34.6 to 37.4 degrees C between 18 and 29 degrees C), whereas udder temperature reached a plateau at 25 degrees C (38.3 degrees C). The gradient of temperature between skin and rectum was minimal (2 degrees C ) at 27 degrees C and remained constant at 29 degrees C. This constancy coincides with the marked reduction of feed intake. The respiratory rate increased from 26 to 124 breaths/min between 18 and 29 degrees C, and this indicates that the evaporative critical temperature was below 22 degrees C. The BW loss increased from 23 to 35 kg between 18 and 29 degrees C, but its estimated chemical composition remained constant. Pig growth rate was almost constant between 18 and 25 degrees C (241 g/d) and was reduced above 25 degrees C (212 and 189 g/d at 27 and 29 degrees C, respectively). In conclusion, temperatures above 25 degrees C seem to be critical for lactating sows in order to maintain their performance.     

Effect of high daytime temperatures on the intake and utilisation of water in lactating Friesian cows

Summary Four primiparous Friesian cows in mid-lactation and housed in climate chambers were simultaneously exposed to three sequential climate treatments: 1, a three-week period in a thermoneutral environment (ambient temperatureT _a 14–21°C and relative humidity r.h. 60–70%); 2, a similar period during which they were exposed toT _a max. 38°C/r.h. max. 80% for up to 7h andT _a 14–21°C/r.h., 60–70% for 17h each day; and 3, a three-week period during which they were subjected once more to the thermoneutral conditions described for 1. Water and a complete feed were constantly available. Compared with water intake (drinking water+feed water) under thermoneutral conditions cows exposed to treatment 2 significantly increased their mean intake by 12.2%; in three cows, this involved a phase-shift of >20% in drinking habits from day (hot) to night (cool) time. Water balance trials conducted at the mid-point of each treatment revealed that the mean losses of water via urine, faeces, milk, sweat and saliva as a percentage of water intake changed significantly resulting in a net gain (retention) of body water. An accompanying significant increase in live weight despite a 9.1% decrease in DM intake during treatment 2 confirmed the water retention results. On return to thermoneutral conditions (3), the cows exhibited a marked weight loss and a significant increase in urinary water excretion over treatment 1 and 2 values, signifying that a large proportion of the water retained during 2 was of extracellular origin. A positive correlation was found between the severity of the clinical and behavioural responses of the individual cows during 2 and their retention of water.

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Resumen Cuatro vacas Friesian primíparas, en la mitad de la lactancia, fueron expuestas en cabinas climáticas a tres tratamientos diferentes consecutivos: I—a un período de tres semanas en un ambiente termoneutro (temperatura ambiente, Ta 14–21°C y humedad relativa HR 60–70%); II—durante período similar, fueron expuestas a una Ta máxima de 38°C/HR máxima de 80% por siete horas y Ta 14–21°C/HR 60–70% por diecisiete horas cada día; y III—durante un período de tres semanas fueron sometidas otra vez a las condiciones termoneutras descritas en el tratamiento I. Agua y un alimento completo estuvieron siempre a disposición. Comparado con el consumo de agua (agua de bebida+agua de alimento) bajo condiciones termoneutrales, las vacas sometidas al tratamiento II incrementaron significativamente su consumo medio en un 12.2%; en tres vacas esto significó un cambio de >20% en hábitos de bebida, del día caluroso a la noche tibia. Los ensayos de balance de agua conducidas en la mitad de cada tratamiento, revelaron que las pérdidas medias de agua via orina, heces, leche, sudor y saliva, como porcentaje del agua ingerida cambió significativamente, resultando en una ganancia neta (retención) de agua corporal. Se observó tambien un incremento significativo en peso vivo de 16.8±7.3 (SE) kg/animal, a pesar de la disminución de 9.1% en la igestión de MS durante el tratamienta II, confirmando así la retención de agua. Bajo condiciones termoneutrales (III), las vacas exhibieron pérdida marcada de peso y un incremento significativo en la exreción de agua, sobre los valores de los tratamientos I y II, indicando así que una proporción alta del agua retenida durante II fue de origen extracelular. Se encontró tambien una correlación positiva entre la severidad de las respuestas clínicas y de conducta de las vacas individuales durante II, con la retención de agua.

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Résumé Quatre vaches frisonnes primipares, à mi-lactation et logées dans des chambres climatisées ont été simultanément exposées à 3 traitements climatiques séquentiels: I. une période de 3 semaines dans un environnement thermique neutre (température ambiante, Ta 14–21°C et humidité relative, HR 60–70 p. 100); II. une période similaire pendant laquelle elles étaient exposées à Ta max. 38°C/HR max. 80 p. 100 pendant sept heures et à Ta 14–21°C/HR 60–70 p. 100 pendant dix sept heures chaque jour; et III une période de 3 semaines pendant laquelle elles étaient de nouveau soumises aux conditions thermiques neutres décrites en I. L'eau et un aliment complet étaient constamment disponibles. Par comparaison avec leur absorption totale d'eau (abreuvement plus eau de constitution des aliments) dans des conditions thermiques neutres, les vaches soumises au traitement II ont augmenté significativement leur absorption moyenne de 12,2 p. 100: chez 3 vaches, ceci a entra?né un décalage dans le temps supérieur à 20 p. 100 de l'absorption diurne (période chaude) à l'absorption nocturne (période fra?che). Des essais d'équilibre hydrique effectués au milieu de chaque traitement ont révélé que les pertes moyennes en eau par les urines, les fèces, le lait, la sueur et la salive, en tant que pourcentage de l'eau absorbée changeait de fa?on significative, ce qui s'est traduit par un gain net (retention) d'eau corporelle. Une augmentation significative concommittante du poids vif de 16,8+7,3 (SE) kg par animal, en dépit d'une diminution de 9,1 p. 100 de l'ingestion de MS pendant le traitement II a confirmé les résultats de rétention d'eau. De retour aux conditions thermiques neutres (III) les vaches ont montré une perte de poids marquée et une augmentation significative de l'excrétion d'eau urinaire, par rapport aux valeurs relevées pendant les traitements I et II, ce que signifie qu'une grande proportion de l'eau retenue au cours du traitement II était d'origine extracellulaire. Une corrélation positive a été observée entre la gravité des réponses cliniques et de comportement des individus en II et leur rétention d'eau.

     

Effects of ambient temperature on heat increment of feeding and energy retention in growing broilers maintained at different food intakes

Zero-activity heat production (HP), body temperature (Tb) and energy retention were measured in growing broilers maintained at 5 ambient temperatures (Ta) (14 degrees , 17 degrees , 22 degrees , 27 degrees and 32 degrees C) and at 5 feeding rates (ad libitum intake and 75%, 50%, 25% and 0% (fasting) of ad libitum). Zero-activity HP increased with decreasing Ta and increasing food intake. However, at 14 degrees C, zero-activity HP in birds fed ad libitum and 75% did not show further increase, but those in birds fed less than 75% of ad libitum increased rapidly. Results of the regression of zero-activity HP on Ta ranging from 32 degrees to 17 degrees C indicated that the slope was affected little by food intake, but the intercept decreased with decreasing food intake. Tb increased significantly with increasing food intake. There was little variation with Ta but, at and above 27 degrees C, a slightly increased Tb was observed only in birds fed ad libitum. Overall effects of Ta and food intake on HIF (% TME intake) were not found, but HIF tended to increase with decreasing food intake at 14 degrees C. Total energy retention and energy retention as fat decreased with decreasing Ta and food intake, although energy retention as protein decreased only with decreasing food intake. Results obtained here suggest that availability of TME is affected little by Ta ranging from 32 degrees to 17 degrees C and that HIF is utilised, in part, to maintain Tb at any Ta.     

高铜对雏鸡器官组织病理损害的研究

将420只1日龄艾维菌健雏，随机分为7组，分别饲以含铜量11mg／kg的基础日粮和含铜量分别为100、200、300、400、500和600mg／kg的6种高铜日粮6周，研究高铜对雏鸡的病理损害。结果显示，日粮含铜100和200mg／kg对雏鸡有促生长作用。日粮铜水平达300mg／kg以上时，对雏鸡器官组织造成不同程度的病理损伤，表现为肌胃角质层增厚呈黄褐色；肝呈浅黄色或深褐色，肝细胞脂肪变性；消化道上皮细胞变性坏死；免疫器官和肾、心脏、胰腺、大脑等器官的实质细胞肿胀；淋巴免疫器官体积缩小，淋巴细胞数量减少。超微结构观察发现，肝细胞胞浆和胞核内见有数量不等、大小不一的高电子密度的沉积物；凋亡的淋巴细胞染色质呈花瓣样、半月形或环形，聚集在核膜下。表明，肝、消化道和免疫器官是高铜损害的主要靶器官。     

Sex-based responses of plasma creatine kinase in broilers to thermoneutral constant and cyclic high temperatures

1. The plasma creatine kinase (CK) activities of male and female broilers under different temperature regimens were studied to investigate the suitability of plasma CK as an indicator of muscle damage due to heat exposure (HE). 2. This study characterises the responses of plasma CK concentration of Arbor Acres broilers to thermoneutral (TN) constant (22°C) or warm cyclic (WC) temperatures (ranging from 27·9°C to 37·9°C). 3. The daily mean CK of the females tended to be higher than those of the males, and significant differences in plasma CK were observed between the genders during the first 5-d test period, namely 2-d TN constant and 3-d WC temperatures. 4. During a 5-d HE to the WC regimens, CK of both genders fluctuated with HE time but exhibited somewhat different profiles. Specifically, the daily mean CK of the females was significantly higher on d 5 of HE than any other daily means, whereas significant difference in daily CK of the males occurred on d 4 of HE. 5. Repetitive blood sampling over 5 d of HE had significant effects on the plasma CK of the females regardless of the number of repeated bleeding times. 6. Profiles of the plasma CK for each gender during d 1 of HE were similar to those under the TN condition, implying that heat stress affects the range of broiler plasma CK concentration but with a 1-d lag. 7. Plasma CK activities of female and male broilers showed a response to HE. However, both the gender and the time of blood sampling should be taken into account when plasma CK is used as an indicator of HE for market-size broilers.     

Energy,protein and limiting amino acid requirements of broilers at very high ambient temperature

1. Twenty one diets were formulated to contain three levels of energy (11.7, 12.5 and 13.4 MJ ME/kg), 4 levels of protein (starter 200, 220, 230 and 250 g, grower 180, 200, 220 and 240 g, and finisher 160, 180, 190 and 210 g/kg) and two concentrations of limiting amino acids (proportion of diet and proportion of protein) in each phase of growth, 0 to 3, 3 to 6 and 6 to 8 weeks of age. Each diet was fed to two pens of 15 broilers.

2. The house temperature ranged from 45°C to 51°C as maximum and 17°C to 22°C as minimum; the relative humidity ranged from 19 to 65.

3. Birds fed low energy (11.7 MJ/kg) and high protein (250, 240, 210 g/kg) diets with the National Research Council (1977) inclusion rates of lysine and sulphur amino acids in starting, growing and finishing phases of growth, attained significantly higher weight gains.

4. High energy, high protein (13.4 MJ/kg, 250, 240, 210 g/kg) diets gave greater efficiencies of food utilisation than low energy, low protein (11.7 MJ/kg, 200, 180, 160 g/kg) diets.     

Effect of elevated ambient temperatures on puberty in gilts

Effects of elevated ambient temperature on puberty and related physiological responses were studied in 40 gilts. Group 1 (n = 20) gilts were born in September and Group 2 (n = 20) gilts were born in March. Gilts were placed in environmentally controlled chambers at 140 d of age. After a 10-d acclimation period at 20 degrees C, 35% relative humidity (RH), and 12 h light (L)/12 h dark (D), gilts within each group were randomly assigned to one of two treatments: control (C; 15.6 degrees C, 35% RH, 12 h L/12 h D) or heat stress (HS; 33.3 degrees C, 35% RH, 12 h L/12 h D). Daily detection of estrus with a boar began at 180 d of age and continued for 50 d. All gilts not reaching puberty by 230 d of age received 1,000 IU pregnant mare serum gonadotropin (PMSG) and 7 d later were examined by laparotomy. Rectal temperatures (REC) and respiration rates (RESP) were taken twice daily. Food intake (FI) and water usage (WC) were recorded daily. Blood samples were collected weekly and BW recorded at 150, 190, and 230 d of age. No differences (P greater than .05) were observed due to season of birth. Heat-stressed gilts had greater (P less than .001) REC and RESP and consumed more (P less than .01) water than C gilts. Food intake and ADG were not different between treatments (P greater than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of dietary l-carnitine supplementation on pulmonary hypertension syndrome mortality in broilers exposed to low temperatures

Oxidative stress is involved in the development of pulmonary hypertension syndrome (PHS) in broilers. l-Carnitine has an antiperoxidative effect and supplemental l-carnitine has been revealed to increase broiler heart weight. The present study was conducted to evaluate the effect of an addition of 100 mg/kg l-carnitine to the basal diets on PHS mortality in cold-exposed broilers. Two-hundred and forty mixed-sex broilers were equally assigned to three groups. The control group was reared in normal temperatures throughout the experiment. Starting on day 14 continuing until the end of the experiment, the other two groups were subjected to a step-down temperature programme (by lowering the temperature 1-2 degrees C per day down to 12-14 degrees C) with or without l-carnitine added to the basal diets. Cold exposure increased the right/total ventricle ratio (RV/TV) and plasma malondialdehyde (MDA), reduced superoxide dismutase (SOD) and led to pulmonary vascular remodelling in birds without feeding additional l-carnitine. Supplemental l-carnitine reduced plasma MDA, increased SOD, inhibited remodelling and postponed the occurrence of PHS for 1 week in cold-exposed broilers; nevertheless, it did not significantly influence the cumulative PHS mortality (p > 0.05). On days 24 and 32, birds fed supplemental l-carnitine had lower RV/TV and higher total ventricle/body weight (p < 0.05) but unchanged right ventricle/body weight ratios (p > 0.05) compared to their cold-exposed counterparts, indicating an increase in left ventricle weight. However, from day 39 on, their RV/TV ratios were suddenly increased (p < 0.05). It was suggested that the l-carnitine-induced increase in left heart weight might partially account for the postponed occurrence of pulmonary hypertension in the early stage by elevating cardiac output, which might, in turn, lead to the resulting increase in pulmonary pressure. In view of its complex effects on cardiopulmonary haemodynamics, l-carnitine supplementation may be impractical for reducing PHS.     

Effect of dietary amino acids and metabolisable energy on the performance of broilers kept at high temperatures

Increasing dietary metabolisable energy (ME) at particular amino acid: ME ratios significantly improved growth and food utilisation of broilers kept at moderate (18 to 26 degrees C) and high (25 to 35 degrees C) ambient temperatures during the finishing period from 22 d of age. The optimum amino acid: ME ratio varied with dietary ME concentration in the hot, but not in the moderate environment. Relatively greater increases in food intake and growth rate occurred in the hot environment when dietary ME was increased and the amino acid: ME ratio was reduced. The minimum rate of food intake did not coincide with the period of maximum temperature. Increasing the dietary protein at particular ME concentrations had little or no effect on the food intake and growth rate of birds kept at high temperatures. Supplementation with dietary fat had no beneficial effect on performance at high temperatures. The rectal temperatures of birds in the hot environment increased with age and, towards the end of the finishing period, when higher energy diets were fed.     

Effect of probiotic supplementation on growth,nitrogen utilisation and serum cholesterol in broilers

1. The effect of dietary probiotic supplementation on the growth, nitrogen utilisation and serum cholesterol content of broiler chickens was studied in 2 trials.

2. In experiment 1, the birds receiving the 0, 75, 100, 125 mg probiotic/kg diets had weight gains of 1204.0, 1272.0, 1268.3 and 1210.5 g, respectively at the end of 8 weeks of feeding. The group of birds fed on the 75 mg probiotic supplemented diet retained significantly (P<0.01) more nitrogen than the control birds. Serum cholesterol content was lower in the probiotic‐supplemented birds (93.3 mg/100 ml) compared to the control birds (132.2 mg/100 ml).

3. In the second experiment the probiotic plus antibiotic‐supplemented group of birds had the maximum weight gain (1148.5 g) followed by antibiotic (1141.3 g), probiotic‐supplemented (1128.4 g) and control birds (1045.6 g) after 6 weeks. Nitrogen retention was greatest in the antibiotic—(48.5%) followed by the probiotic—(46.5%), probiotic plus antibiotic‐supplemented groups (46.3%) compared to 40.2% in control birds.

4. The apparent metabolisable energy was greatest in birds receiving the probiotic plus antibiotic‐supplemented diet (12.37 MJ/kg) followed by antibiotic—(12.00 MJ/kg), probiotic‐supplemented birds (11.92 MJ/kg) than in control birds (11.62 MJ/kg). Serum cholesterol was significantly (P<0.01) lower in probiotic‐supplemented birds (86.1 mg/dl) compared to 118.4 mg/dl in control birds.     

Application of an early skip-a-day feed restriction on physiological parameters, carcass traits and development of ascites in male broilers reared under regular or cold temperatures at high altitude

The present study was conducted to evaluate the effects of a skip‐a‐day feed removal early in life on physiological parameters and ascites occurrence in broilers reared at a high altitude (2100 m above sealevel) under regular or cold temperatures. Three hundred 1‐day‐old male broilers were divided into two equal groups. One group was placed in an enclosure with standard thermal management. The other group treated for the induction of ascites was raised under cold temperature conditions. In each enclosure, birds were randomly assigned to one of two treatment groups (three replicate floor pens of 25 chicks per treatment group): (i) a control was fed a standard starter and grower diet according to the National Research Council; or (ii) a skip‐a‐day feed removal, which was similar to the control except for 24 h fasting intervals at 9, 11 and 13 days of age. Results indicate that live bodyweight following the feed removal at up to 42 days of age was significantly different between the control and skip‐a‐day restricted birds (P < 0.01). Skip‐a‐day feed removal resulted in decreased weight gain (P = 0.005) but did not influence feed conversion ratio. The heterophil : lymphocyte ratio was numerically higher for the cold environment and increased when birds were exposed to fasting, but these differences were not significant. Hematocrit was significantly higher (P = 0.0001) in broilers raised in cold conditions whereas it was not influenced by feed restriction. Circulatory thyroid hormone concentrations were not influenced by the feed restriction program under both environments. Birds subjected to cold had significantly lower (P = 0.0023) carcass yield compared to those reared at normal temperature. Breast yield and abdominal fat deposition were not influenced by cold or feed restriction. A reduction in mortality from ascites was noted in broilers who experienced early skip‐a‐day feed removal under both environmental conditions.